The present invention relates to a print activator test circuit and particularly to testing the operativeness or inoperativeness of electrical circuits involved in a printing operation without actually effecting printing during the test process.
In printers where a mechanical member such as a print wire is actuated by an electromagnet, it may be of paramount importance to provide means for checking that electrical circuits involved in actuating the printing elements are in an operative state. Where the actuating apparatus involves electromagnets, it is important to determine before printing commences that an open or shorted coil exists. It is desirable that this test of operativeness occur without having dots or other indicia printed during the test process.
Arrangements are known whereby the accomplishment of the above testing is checked by independent detecting members sensitive, for example, to mechanical motions of such apparatus as printing styli, optical or piezoelectric moving elements or the like. Unfortunately, these types of arrangements are complex and expensive, especially in the case of high speed parallel printing where the number of actuators is very high. In case of serial printers, for example of the dot matrix type, a plurality of stylus drivers are employed and the same problems and considerations are involved. The result of these aforementioned schemes is that it involves a multiplicity of independent detection means, mechanical connections of undue complexity, increased weight, increased space requirements and masking by failures occurring in other parts of the system.
The object of the invention is to obviate such problems by providing a control arrangement for detecting the operativeness of an electrical circuit by employing a driving signal of shortened duration sufficient to produce a driver signal output to indicate operativeness or inoperativeness but not sufficient to cause printing by an associated printing element and a common detection means.